HP e-CommerceXML Accelerator sa7150 - Manual (Page 42)

C H A P T E R 3 HP e-Commerce/XML Server Accelerator SA7150 User Guide
32
Multiple
SA7150s and
Cascading Scalability and Cascading
The SA7150’s capabilities are scalable by chaining, or “cascading,”
multiple SA7150s together. In such configurations, each unit’s server
side connector is wired to the network side connector of the next
SA7150 in line. The last SA7150 in line is connected to the server or
switch.
Cascaded SA7150s
Spilling and Throttling
NOTE: The SA7150
restarts when spill is
enabled. Depending on
the size of the current
configuration file, it can
require from 30 seconds
to seven minutes to return
to operations. When the SA7150’s “spill” option is enabled, if a given SA7150
cannot process a request within a specified interval, the request is
passed on to the next SA7150 in line. The last SA7150 on the server
side can also be enabled to spill to the server. Spilling is performed
dynamically on a connection-by-connection basis. (See spill
command, Chapter 5, “Command Reference.”) If spill is disabled, the
SA7150 “throttles,” that is, does not accept incoming requests when
it becomes overloaded.
Availability
When a SA7150 fails or is set to Bypass mode while Fail-through is
enabled, the SA7150’s network side and server side network adapters
are directly connected, allowing traffic to pass through to the next
device until the failed unit is brought back into service. This feature
eliminates a single point of failure and provides a high level of
availability, should there be a failure. See “Failure/Bypass Modes” in
Appendix B for more information.
XML Server 1
XML Server 2
XML Server 3
hub/switch Router
HP e-Commerce/XML Server
Accelerator SA7150
HP e-Commerce/XML Server
Accelerator SA7150